CN112005019A

CN112005019A - Adjustable bail extension

Info

Publication number: CN112005019A
Application number: CN201980027254.3A
Authority: CN
Inventors: M.W.斯莱克; M.艾伦; M.希恩; K.莫里尔
Original assignee: Noetic Technologies Inc
Current assignee: Noetic Technologies Inc
Priority date: 2018-04-27
Filing date: 2019-04-29
Publication date: 2020-11-27
Anticipated expiration: 2039-04-29
Also published as: EP3784912A1; US20200056649A1; CA3097431A1; WO2019204897A1; AU2019258608A1; EP3784912A4; US10982711B2; CA3092657A1; CA3092657C; CN112005019B

Abstract

An adjustable bail extension includes a tubular outer link, an inner link disposed within an aperture of the outer link and axially movable therein, and an adjustment mechanism for releasably clamping the outer link to the inner link in any one of a plurality of locked positions defined by sets of locking slots formed at axially spaced intervals on the inner link. The adjustment mechanism is operable between a locked position in which a collet assembly coupled to the outer link engages a selected set of locking grooves enabling axial load transfer between the inner and outer links; in the unlocked position, the collet assembly is not operably engaged with any of the inner link slots such that the inner link is axially movable within the outer link, thereby enabling adjustment of the overall length of the adjustable bail extension by repositioning the collet assembly to engage the inner link slot in another, different, locked position.

Description

Adjustable bail extension

Technical Field

The present disclosure relates generally to length adjustable structural members capable of carrying axial loads at a variety of working lengths. More particularly, the present disclosure relates to adjustable extensions for bails of drill pipe elevators commonly used for handling tubulars during drilling and casing of oil and gas wells.

Background

Previously, the use of power tongs in conjunction with a rig hoist system has been the established method of installing pipe strings (e.g., drill string and casing string) in an oil well. The method allows for relatively efficient make-up of such tubular strings comprising tubular segments (or "subs") having mating threaded ends using power tongs as a means of threading the threaded ends of the tubular joints together to form a threaded connection between sequential joints as sequential joints are added to the tubular string being made up and installed in the wellbore (i.e., "make-up" operations); or conversely for unscrewing the threaded connections to remove the sub in order to break down the string pulled out of the wellbore (i.e., "break-out" operations). This method requires two separate systems, namely a power tong for make-up and break-out operations and a rig-lifting system for lifting and lowering the casing string.

Modern drilling rigs typically utilize a top drive, the primary purpose of which is to achieve efficient oil well drilling, and which has previously not been fully utilized during casing operations (i.e., installation of a tubular casing string into a wellbore). Drilling rigs equipped with a top drive implement a new casing running method using a tool commonly referred to as a casing running tool (or "CRT"). These tools are adapted to be mounted and hung onto the top drive quill and grip the upper end of the tubular casing joint and provide a seal between the bore of the gripped casing joint and the bore of the top drive quill. The CRT is matched with a top drive device to support make-up and break-out operations and the lifting and lowering of the casing string so that no power tongs need to be used for make-up and break-out operations of the casing.

The top drive provides two load paths capable of supporting the weight of the pipe string and its components. During drilling operations (including "drill-while-pipe" operations), the weight of the tubular drill string is carried by the top drive through a top drive quill, which is typically designed to support the full weight of the drill string. During make-up and break-out operations, the weight of each joint added to or removed from the pipe string is transferred to the top drive by a pair of "ears" disposed on opposite sides of the top drive and a conventional pipe elevator equipped with a pair of connecting rods (also commonly referred to as "bails"). Each link (or bail) is formed with an "eye" at each end, one of which is configured for rotational engagement with one ear on the top drive and the other of which is configured for rotational engagement with the elevator, so that the top drive can be used to add a tubular sub carried by the elevator to a tubular string being assembled during a make-up operation, or to remove a sub from the string during a break-out operation.

Thus, using a CRT allows the top drive quill to carry the full weight of the casing string so that the links and elevator do not have to carry the full weight of the casing string as in conventional operations that do not use a CRT. The links and elevator still have the important function of lifting the casing joint from the V-door at the drill floor into the rig structure in preparation for assembly into the casing string. The top drive is traditionally equipped with a shorter connecting rod designed for drilling operations, the end of which is close to the top drive quill. Mounting the CRT and the mating accessories to the top drive quill requires replacing the links with longer links, which can be expensive and time consuming; or the addition of an extension to an existing link, which is faster and less expensive than replacing the link.

The bail extensions must be long enough to ensure clearance between the CRT and the sleeve joint carried by the elevator, but too much clearance can make it difficult to insert the CRT into the sleeve joint. The appropriate length of the bail extension in a given situation depends on a number of variables, including the length of the particular CRT used and any accessories mounted in conjunction therewith (e.g., the adapter joint required to mate the CRT to the top drive sleeve shaft), as well as additional equipment mounted between the sleeve shaft and the CRT (e.g., a torque monitoring joint). Due to all these variables, a single bail extension length cannot be adapted to all operating environments.

In the prior art, the variability of bail extension length parameters is addressed by using a bail extension having two telescoping members with matching transverse holes, which allows the telescoping members to be rigidly connected at discrete axial positions by bolts or pins passing through the matching transverse bolt holes. However, this type of connection has a load efficiency (where load efficiency is defined as the ratio of the axial load capacity of the connection to the basic axial load capacity of the telescopic member) that is too low due to the loss of cross section of the telescopic member at the bolt hole. The bolted or pinned connections between the telescopic parts therefore limit their load-bearing capacity, and they must therefore be larger and heavier than would otherwise be necessary, thereby making the manufacture, transport and handling of such variable length linkages more difficult.

Disclosure of Invention

The present disclosure presents embodiments of a bail extension that is adjustable in length to accommodate changes in link length requirements inherent in CRT operation. These adjustable bail extensions utilize an adjustment mechanism that is more load efficient than conventional adjustable bail extensions, thereby making the adjustable bail extensions lighter in weight than conventional adjustable bail extensions having similar lifting capabilities. The length of the extension does not need to be adjusted by removing parts of the adjustable bail extension, thus eliminating the risk of loose parts accidentally falling and being lost during adjustment, thereby resulting in costly downtime.

In general, one particular embodiment of the adjustable bail extension of the present invention comprises the following components:

an elongated tubular outer link member having a bore, an open lower end and an upper end with a link adapter (for connection to an existing link suspended from a top drive);

an elongate inner link member (which may be a tubular member or a solid bar) having a lower end with an elevator adapter (for connection to a mounting "ear" on a conventional drill pipe elevator) and an upper end which is axially movable within the bore of the outer link member; and

an adjustment mechanism carried by the outer link member for securely and releasably clamping the outer link member to the inner link member at a selected one of a plurality of locking positions defined by an annular groove provided as a single set or multiple sets of annular grooves formed at discrete axial intervals on a peripheral surface of the inner link member.

The adjustment mechanism is operable between:

a locking position in which the adjustment mechanism engages a selected annular groove (or set of annular grooves) on the inner link member to prevent relative axial movement of the inner and outer link members and to enable axial loads to be transmitted between the inner and outer link members; and

an unlocked position in which the adjustment mechanism is not operatively engaged with any annular groove on the inner link member such that the inner link member is axially movable within the outer link member, thereby enabling adjustment of the length of the adjustable bail extension.

In a first embodiment, the adjustment mechanism includes a collet assembly including a collet base ring with a plurality of collet arms, each collet arm with collet fingers configured for mating engagement with an annular groove on the inner link member. The collet assembly is disposed in coaxial alignment with the outer link member, and the collet base ring engages the lower end of the outer link member. In one variation, the collet assembly is axially fixed relative to the outer link member and optionally may be integrally formed with the outer link member. However, in a preferred embodiment, the collet assembly is physically separated from the outer link member and is axially movable relative to the outer link member within a selected range of travel (or "play") so as to prevent excessive or undesirable axial loads in the collet arms (as described in detail below).

The adjustment mechanism also includes a generally cylindrical locking sleeve coaxially disposed about the outer link member to surround the collet assembly and coupled to the outer link member in a manner that permits limited axial displacement of the locking sleeve relative to the outer link member so as to enable operation of the adjustment mechanism between a locked position and an unlocked position. The locking sleeve has an upper end (i.e., the link adapter end that faces the outer link member when the locking sleeve is mounted on the outer link member), a lower end, and a generally cylindrical bore.

Axial displacement of the locking sleeve relative to the outer link member may be achieved by a threaded connection between these components, but this is merely one non-limiting example. While threaded connections are illustrated and described herein as a means of coupling the locking sleeve to the outer link member and effecting relative axial displacement therebetween, other functionally effective alternative means (e.g., so-called "latching" mechanisms) may be employed without departing from the scope of the present disclosure.

The lower region of the locking sleeve bore is contoured to matingly engage the complementary contoured radially outer surfaces on the collet fingers to enable axial tensile loads to be transferred from the collet fingers to the locking sleeve in a manner described below when the adjustment mechanism is in the locked position.

When the adjustment mechanism is in the locked position, the collet fingers engage a selected annular groove (or set of annular grooves) on the inner link member, and the radially outer surfaces of the collet fingers matingly engage the complementary contoured surfaces of the locking sleeve bore. The locking sleeve thereby prevents the collet fingers from deflecting radially outward, allowing for stable transfer of axial tensile loads from the inner link member to the collet fingers (through engagement of the collet fingers with annular grooves in the inner link member), from the collet to the locking sleeve (through engagement of the collet fingers with mating profile surfaces on the locking sleeve bore), and from the locking sleeve to the outer link member (through threaded connections between these components).

To change the overall length of the adjustable bail extension, the locking sleeve may be rotated so that it is axially displaced relative to the outer link member and collet assembly to a degree sufficient to disengage the collet fingers from the contoured area of the locking sleeve bore, thereby enabling the collet fingers to disengage from the annular groove on the inner link member to move the adjustment mechanism from the locked position to the unlocked position. An axial force (pressure or tension applied as needed) may then be applied to axially displace the inner link member relative to the outer link member to disengage the collet fingers from the one or more annular grooves in the inner link member to change the overall length of the adjustable bail extension.

The collet assembly may be manufactured such that the collet arms are resiliently biased in a radially inward direction such that as the inner link member is moved to a new position, the collet fingers will tend to engage the annular groove through which they pass. However, such biasing of the collet arms preferably does not exceed the degree of biasing that is reasonably required for the collet fingers to engage in the annular groove, so as to minimize the axial load that needs to be applied to the adjustable bail extension in order to move the collet fingers and enable adjustment of the adjustable bail extension.

In one variation, the collet assembly may be manufactured such that the collet arms have a neutral radial bias such that the collet fingers do not engage the annular groove on the inner link member unless they are forced into engagement by the locking ring being tightened to exert a radially inward force component on the collet fingers. In this embodiment, the collet fingers do not provide resistance to relative axial displacement of the inner and outer link members when adjusting the overall length of the adjustable bail extension, which may be advantageous in situations where the adjustment mechanism operates with the adjustable bail extension in a horizontal orientation.

To prevent accidental axial displacement of the locking sleeve when the adjustment mechanism is in the locked position, a locking pin or locking bolt (or other functionally effective locking means) may be used to temporarily prevent excessive rotation of the locking sleeve and the associated excessive axial movement towards the unlocked position that results therefrom. Such a locking device is preferably not removable from the locking sleeve, for example by tethering it to the locking sleeve with a rope.

In some embodiments, the inner and outer links of the adjustable bail extension may have cylindrical outer surfaces at least in the area where they will engage the adjustment mechanism. In such a case, the collet assembly would have a generally cylindrical configuration with the collet fingers defining a generally cylindrical collet bore and configured to engage a circular (i.e., annular) groove on the cylindrical surface of the inner link. However, the scope of the present disclosure is not limited to such embodiments, and in alternate embodiments, at least a portion of the inner and outer links may have a non-cylindrical outer surface. For example, the cross-section of the portion of the inner link with the grooves for engagement with the collet fingers may be non-circular (e.g., linear, polygonal, or elliptical), and the arrangement and configuration of the collet arms adjusted accordingly.

The present disclosure illustrates and shows embodiments specifically configured for use in conjunction with links or bails of conventional drill pipe elevators used on drilling rigs in the oil and gas industry. However, the teachings of the present disclosure are readily applicable to other types of elongated structural members having desired or required length adjustment capabilities, and the scope of the present disclosure is intended to extend to such alternative applications. Non-limiting examples of such alternative applications are tubular struts in scaffolding systems, and struts and secondary struts used during the construction of multi-storey reinforced concrete buildings.

Thus, in general, the present disclosure proposes a variable-length structural element comprising:

an elongate tubular outer member having a first end and a second end, the first end of the outer member being open to the bore of the outer member;

an elongate inner member having a first end and a second end, the first end of the inner member being coaxially disposed within the bore of the outer member; and

an adjustment mechanism coupled to the outer member and comprising an inner member locking arrangement, the adjustment mechanism being operable between: (1) a locking position in which the inner member locking means engages the inner member at a selected locking position on the inner member to prevent relative axial movement of the inner and outer members and thereby enable axial loads to be transmitted between the inner and outer members; and (2) an unlocked position in which the inner member locking means does not prevent relative axial movement of the inner and outer members.

In one embodiment of the variable length structural element, the inner member locking means comprises:

a collet assembly having a collet bore and comprising a collet base ring coaxially coupled with the first end of the outer member so as to be axially movable therewith, wherein: (1) a collet base ring with a plurality of collet arms extending axially away from the first end of the outer member; (2) each collet arm with collet fingers configured to engage locking grooves formed on an outer surface of the inner member; and (3) the inner member passes coaxially through the collet bore; and

a cylindrical locking sleeve having a locking sleeve bore between an open first end and an open second end of the locking sleeve, wherein: (1) a locking sleeve coaxially surrounding the collet assembly, a portion of the locking sleeve proximate the second end coaxially overlapping the first end of the outer member and the first end of the locking sleeve extending beyond the first end of the outer member; (2) the locking sleeve is coupled to the outer member by a locking sleeve coupling arrangement allowing axial movement of the locking sleeve relative to the outer member within a defined range, thereby enabling operation of the adjustment mechanism between a locked position and an unlocked position; and (3) the region of the locking sleeve bore proximate the first end of the locking sleeve is contoured to engage the radially outer surface of the complementary contour on the collet fingers when the adjustment mechanism is in the locked position.

The collet bore may be generally cylindrical and the locking groove is an annular groove formed on the cylindrical outer surface of the inner member. In an alternative embodiment, the outer surface of the inner member may be non-circular in the region of the inner member with the locking groove.

The locking sleeve coupling means may be in the form of female (or "internal" threads) formed in a locking sleeve bore adjacent the second end of the locking sleeve and mating male (or "external" threads) formed on the outer member adjacent the first end of the outer member.

The locking mechanism may comprise axial restraint means for restraining axial movement of the locking sleeve relative to the outer member when the adjustment mechanism is in the locked position. Such axial restraint means may include a locking pin slot disposed on the outer surface of the outer member, and a transverse locking pin hole disposed within the locking sleeve for retractably inserting the locking pin for engagement with the locking pin slot within a selected range of axial positions corresponding to the locking position of the adjustment mechanism.

Alternatively, the axial restraining means may comprise a set screw acting between the locking sleeve and the outer member, or, more advantageously, may comprise a threaded locking dog mounted in the locking sleeve and engageable with a locking dog recess formed in the outer surface of the outer member over a selected range of axial positions corresponding to the locking position of the adjustment means in a manner well known in the art.

The inner member may be a solid rod or tubular member, and in either case, the cross-section of the inner member need not necessarily be circular. Also, the tubular outer member does not necessarily have to be a circular tube. However, where the cross-section of the outer member is not circular, it may have an axially symmetric outer surface in any region where it is desired to form a thread.

The present disclosure also proposes a variable length structural element substantially as described above, but configured for use as an adjustable bail extension for use with a drill pipe elevator, for make-up and break-out of pipe strings in the oil and gas industry.

Drawings

Embodiments of the invention will now be described with reference to the drawings, wherein like reference numerals represent like parts, in which:

FIG. 1A is a schematic view of a top drive apparatus engaged with a conventional pipe elevator, showing the top drive apparatus supporting a casing joint in conjunction with the use of an adjustable bail extension of the present disclosure;

FIG. 1B is a side view of the equipment assembly shown in FIG. 1A;

FIG. 2 is an isometric view of one embodiment of the adjustable bail extension of the present invention;

FIG. 3A is a longitudinal cross-sectional view of one embodiment of an adjustment mechanism of the present disclosure, wherein the adjustment mechanism is shown in a locked position;

FIG. 3B is a longitudinal cross-sectional view of the adjustment mechanism of FIG. 3A, with the adjustment mechanism in an unlocked position;

FIG. 3C is a longitudinal cross-sectional view of the adjustment mechanism of FIGS. 3A and 3B, with the adjustment mechanism shown between a locked position and an unlocked position;

FIG. 4 is an isometric view of the collet assembly of the bail extension shown in FIG. 2;

figure 5 is an isometric view of a lower portion of the outer link member end of the bail extension shown in figure 2.

Detailed Description

In this patent document, the terms "upper", "lower", "upward" and "downward" when used with reference to a component or feature of the disclosed adjustable bail extension or with reference to relative movement or displacement of components of the adjustable bail extension should be understood to correspond to the vertical orientation of the bail extension as shown in fig. 1A and 1B.

Fig. 1A and 1B schematically illustrate a typical equipment setup for running a tubular (e.g., casing joint) (i.e., make-up of a casing string) or breaking up a casing string (i.e., break-out) into a wellbore using a top drive 10 having a top drive sleeve shaft 14, the top drive sleeve shaft 14 shown supporting an internal grip Casing Running Tool (CRT)30 having a gripping assembly 32. The top drive 10 has a pair of "ears" 12, the pair of "ears" 12 being used to support a heavy, integral conventional elevator link (or bail) 20 by way of an upper link eye 22U formed at the upper end of the conventional link 20. A conventional pipe elevator 40 is used to support a casing joint 50 lowered into or extended out of a wellbore by placing the elevator 40 directly below a tubular coupling 60 that is threaded onto the upper end of the casing joint 50. The pipe elevator 40 has a pair of ears 42, the ears 42 having apertures for receiving a hook 44 or other suitable metal piece to engage the lower link eye 22L formed at the lower end of the conventional link 20.

As can be readily appreciated from fig. 1A and 1B, if the CRT30 (or other device having a substantial overall vertical length) is not suspended from the top drive sleeve shaft 14, the conventional connecting rod 20 can directly engage the hanger ear 42 as described above. However, because of the vertical length of the CRT10 (and possible additional accessories), the link 20 in fig. 1A and 1B is too short to reach the elevator 40. It is often impractical to remove a heavy conventional link 20 from the top drive 10 and replace it with a longer link, so an extension must be provided to make up for the gap between the lower link eye 22L of the link 20 and the elevator ear 42. Fig. 1A and 1B illustrate an adjustable bail extension 100 of the present invention for this purpose.

In the embodiment shown in fig. 2, each of the two adjustable bail extensions 100 includes:

an elongated tubular outer link member (or "outer link") 300 having a bore 315, an open lower end 300L, and an upper end 300U with link adapter 200;

an elongated inner link member (or "inner link") 500 having a lower end 500L with an elevator adapter 200; and

an adjustment mechanism 400 carried by the outer link 300 for releasably clamping the outer link 300 to the inner link 500 in a selected locked position on the inner link 500.

In the illustrated embodiment, the link adapter 200 is shown as a carabineer-type shackle, but this is merely one non-limiting example; the link adapter 200 may take other functionally effective forms without departing from the scope of the present disclosure. Similarly, the elevator adapter 600 is shown as a solid connector having holes for receiving bolts, cotter pins, or other suitable fasteners, but may be in any other functionally effective form.

When the bail extension 100 is used for top drive operation as shown in fig. 1A and 1B, the upper end 300U of the outer link 300 is connected to the lower link aperture 22L on the conventional link 20 through the link adapter 200. Similarly, the lower end 500L of the inner link 500 is connected to the elevator ear 42 on the pipe elevator 40 by an elevator adapter 600. The bail extension 100 is typically used only to support the weight of casing joints added to or removed from a casing string. As the casing string is lowered (during make-up operations) or raised (during break-out operations), the full weight of the casing string will be transferred directly to the top drive 10 through the CRT 30. Thus, the bail extension 100 is typically subjected to only axial tensile loads during normal operation, and, because these tensile loads are relatively small, the bail extension 100 need not be as heavy as conventional links.

The outer link 300, adjustment mechanism 400 and inner link 500 are generally configured as a set of coaxially nested, close-fitting, generally cylindrical components. The adjustment mechanism 400 is operable between a locked position, as shown in fig. 3A, and an unlocked position, as shown in fig. 3B. In the locked position, the axial load applied to the bail extension 100 is transferred between the outer link 300 and the inner link 500 through the adjustment mechanism 400, and the overall length of the bail extension 100 is unchanged. In the unlocked position, the inner link 500 may be partially extended from the outer link 300 or partially retracted into the outer link 300 to enable adjustment of the overall length of the bail extension 100.

In the embodiment shown in fig. 3A, 3B and 3C, adjustment mechanism 400 includes a collet assembly 420 having a collet bore 450, a locking sleeve 440 and a locking pin 460, which are generally configured as a set of coaxially nested, close-fitting, generally cylindrical components. The locking sleeve 440 has an upper end 440U, a lower end 440L, and a locking sleeve bore 445, and is mounted around the outer link 300 so as to be axially movable relative to the outer link 300. In the illustrated embodiment, this function is provided by a male thread (or "external thread") 302 formed on a lower region of the outer link 300 and a mating female thread (or "internal thread") 442 formed in an upper region of the locking sleeve bore 445.

As shown in fig. 3A, 3B, 3C and 4, collet assembly 420 has a collet base ring 421, which collet base ring 421 has a plurality of collet arms 422 projecting downward from collet base ring 421 and spaced evenly around collet base ring 421. Each collet arm 422 carries a collet finger 423, which collet finger 423 comprises a plurality of annular collet projections 429 projecting radially inwardly and forming a set of collet projections 430. As can best be seen in fig. 3C, each collet projection 429 has a collet extension side 424 and a collet retraction side 425. Each collet projection 429 is configured to fit snugly into a corresponding one of a plurality of annular grooves 505 formed on the outer cylindrical surface 504 of the inner link 500 and constituting a set of inner link grooves 510. As can best be seen in fig. 3A, each annular groove 500 includes an annular inner link extension side 502 (engageable with collet extension sides 424 on collet fingers 423) and an annular inner link retraction side 503 (engageable with collet retraction sides 425 on collet fingers 423). Multiple sets of inner link slots 510 are provided at selected locking positions along the inner link 500 to define the length adjustment intervals and total length adjustment range that can be used for a given configuration of adjustable bail extension 100.

In the particular embodiment shown in fig. 3A, 3B and 3C, the set of collet projections 430 on each collet finger 423 has three identical annular collet projections 429 and each set of annular grooves 510 on the inner link 500 has three identical annular grooves 505. However, this is only a non-limiting example. The number, size and shape of the annular grooves 505 and collet projections 429 can be selected to control local stresses within the component size limits, and depending on these factors, it may be sufficient in some applications to include only one groove or projection per "set" of grooves or projections. In some cases, it may be desirable that the configuration of the collet projections and annular grooves in each set of collet projections 430 and each set of grooves 510 be different to ensure that only one engagement position is possible. Similarly, the cross-section of each set of annular grooves 510 need not be circular. With a non-circular cross-section selected, a means of ensuring rotational alignment between collet assembly 420 and inner link 300 may be provided.

As shown most clearly in fig. 3B, 3C and 4, the radially outer surface of each collet finger 423 is further configured to define a plurality of collet finger load sides 426 engageable with locking sleeve load sides 444 formed in a lower region of the locking sleeve bore 445.

In the embodiment shown in fig. 3C, collet arms 422 are designed to deflect under radial load to facilitate engagement of the sets of collet projections 430 in the sets of slots 510. It should be appreciated that the geometry of collet assembly 420 (including the length, width, thickness, material and number of collet arms 422 and the length and thickness of base ring 421) may be selected to define the load deflection response of collet arms 422. Applying a tensile load (or "extension load") to increase the amount of extension of the inner link 500 relative to the outer link 300 (and thereby increase the length of the adjustable bail extension 100) causes the collet extension sides 424 to contact the inner link extension sides 502, and the geometry of this contact causes a radial load on the collet fingers 423, forcing the collet fingers 423 radially outward. Similarly, applying a compressive load (or "contraction load") to retract the inner link 500 further into the outer link 300 (and thereby reduce the length of the adjustable bail extension 100) causes the collet retraction sides 425 to contact the inner link retraction sides 503, and the geometry of this contact causes a radially outward load on the collet fingers 423, forcing a corresponding radial deflection of the collet fingers 423. With the adjustment mechanism 400 in the unlocked position, application of sufficient extension or retraction load accompanied by axial displacement causes the set of collet projections 430 to disengage from the previously engaged set of inner link slots 510 such that the set of collet projections 430 is in sliding contact with the outer cylindrical surface 504 of the inner link 500.

Referring now to FIG. 4, the seating ring 421 on collet assembly 420 has a plurality of seating ring extensions 427 that project upward from seating ring 421 and are evenly spaced around seating ring 421, forming seating ring recesses 435 between adjacent seating ring extensions 427 and forming upwardly facing seating ring shoulders 432 that extend between adjacent seating ring link extensions 427. Collet ring flanges 427F extend radially outward from each base ring extension 427 and define downwardly facing collet ring flange shoulders 428 such that all collet ring flange shoulders 428 lie in a common plane transverse to the longitudinal axis of collet assembly 420. Similarly, each collet ring flange 427F defines an upwardly facing collet ring flange face 437 such that all collet ring flange faces 437 lie in a common plane transverse to the longitudinal axis of the collet assembly 420.

Referring now to FIG. 5, the outer link 300 has a plurality of outer link extensions 304 projecting downward from the lower end 300L of the outer link 300 and evenly spaced about the lower end 300L, forming outer link wall recesses 335 between adjacent outer link extensions 304 and forming downward facing outer link shoulders 337 extending between adjacent outer link extensions 304. Outer link flange 304F extends radially outward from each outer link extension 304 and has an upwardly facing outer link flange shoulder 305 such that all outer link flange shoulders 305 lie in a common plane transverse to the longitudinal axis of collet assembly 420. Similarly, each outer link flange 304F defines a downwardly facing outer link flange face 306 such that all outer link flange faces 306 lie in a common plane transverse to the longitudinal axis of collet assembly 420.

Referring again to fig. 3A, 3B and 3C, it can be seen that when adjustment mechanism 400 is fully assembled and in the locked position, outer link extensions 304 project into corresponding base ring recesses 435 on collet assembly 420 and base ring extensions 427 on collet assembly 420 project into corresponding outer link wall recesses 335 such that the plane of downward facing collet ring flange shoulder 428 is above the plane of upward facing outer link flange shoulder 305, thereby forming an annular gap G between collet ring flange shoulder 428 and outer link flange shoulder 428. A collet retainer ring 480 is disposed within the annular gap G, the axial thickness of the collet retainer ring 480 being less than the maximum axial length of the annular gap G, such that the collet retainer ring 480 is within the gap G in a loose fit, providing a range of axial movement (also referred to as "play") for the collet assembly 420 relative to the outer link 300.

Application of an axial tensile load reacted through collet fingers 423 of collet assembly 420 will tend to cause annular gap G to decrease to within a limit that clamps collet retainer ring 480 between collet ring flange shoulder 428 and outer link flange shoulder 305 (as shown in fig. 3C), effectively transferring the axial tensile load directly to outer link 300.

Similarly, depending on the particular configuration of the associated components, application of an axial compression load to the collet assembly 420 will tend to cause the annular gap G to increase to a limit where the upwardly facing base ring shoulder 432 contacts the corresponding downwardly facing outer link flange face 306 or the upwardly facing collet ring flange face 437 contacts the corresponding downwardly facing outer link shoulder 337, thereby effectively transferring the axial compression load to the outer link 300. These components can also be configured such that both extreme conditions occur simultaneously, i.e., base ring shoulder 432 is in contact with the corresponding outer link flange face 306, while collet ring flange face 437 is in contact with the corresponding outer link shoulder 337.

Thus, unless collet assembly 420 is at its limit of play, neither axial tensile loads nor axial compressive loads applied through collet fingers 423 are transmitted to outer link 300 through collet arms 422.

Fig. 3A illustrates adjustment mechanism 400 in a locked position, wherein lock sleeve 440 is threadably engaged with outer link 300 as previously described, such that, in the illustrated embodiment, right-handed (i.e., clockwise) rotation of lock sleeve 440 relative to outer link 300 causes lock sleeve 440 to move upward relative to outer link 300, and left-handed (i.e., counterclockwise) rotation of lock sleeve 440 relative to outer link 300 causes lock sleeve 440 to move downward relative to outer link 300. Locking pins 460 are shown disposed within locking sleeve pin holes 441 to engage circumferential locking pin slots 303 formed on the cylindrical outer surface 310 of the outer link 300 to prevent accidental withdrawal of the locking sleeve 440 when the adjustable bail extension 100 is in use.

To move the locking mechanism 400 to the unlocked position, the locking pin 460 may be withdrawn or retracted from the locking sleeve pin hole 441 and then the locking sleeve 440 may be rotated counterclockwise, thereby releasing the collet fingers 423 from the previously engaged set of annular grooves 510. While the locking pin 460 is shown as a straight pin, this is merely one non-limiting example, and the component may be provided in any functionally effective form without departing from the intended scope of the present disclosure. In some cases, as another example, the locking pin 460 may be provided in the form of an eccentric pin that is rotationally adjustable between an engaged position and a disengaged position without being removed from the locking sleeve 400, thereby eliminating the risk of the locking sleeve pin hole 441 being lost and possibly even accidentally dropped into the wellbore or casing string.

In the illustrated embodiment, the play of collet assembly 420 relative to outer link 300 is greater than the allowable axial displacement of locking pin 460 within locking sleeve pin hole 441 relative to locking sleeve 440. This feature ensures that contact is maintained between collet finger load sides 426 and locking sleeve load sides 444 and that tensile lifting loads transferred from inner link 500 to collet assembly 420 are always transferred via collet finger load sides 426 rather than via collet arms 422, allowing collet arms 422 to be designed independently to allow radial deflection of collet fingers 423 during adjustment.

Referring specifically to fig. 3A and 3B, it can be seen that the relative axial positions of the collet finger load side 426 and the locking sleeve load side 444 define two operating positions of the adjustment mechanism 400 as follows:

in the locked position (as shown in fig. 3A), the collet finger load side 426 engages the lock sleeve load side 444 and the lock pin 460 is within the lock sleeve pin hole 441 in the lock sleeve 440, thereby engaging the lock pin slot 303 on the outer link 300. The radial deflection of the collet fingers 423 is constrained by the close fitting engagement of the collet fingers 423 with the locking sleeve 440 due to the application of the lifting load, such that the axial load can be transferred in turn from the inner connecting rod 500 to the collet fingers 423, then to the locking sleeve 440, and finally to the outer connecting rod 300.

In the unlocked position (as shown in fig. 3B), the collet finger load side 426 is disengaged from the lock sleeve load side 444 and the lock pin 460 has been removed or retracted from the lock sleeve pin hole 441. Application of sufficient extension or contraction load causes the collet fingers 423 to deflect radially, thereby allowing one set of collet projections 430 to move axially between each set of inner link slots 510.

The process of adjusting the overall length of the adjustable bail extension 100 may be summarized as follows:

starting from the locked position (as shown in fig. 3A), the locking pin 460 is removed from the locking sleeve pin hole 441, and the locking sleeve 440 is rotated counterclockwise and thereby displaced downward relative to the outer link 300 until the adjustment mechanism 400 is in the unlocked position (as shown in fig. 3B). An extension or retraction load may then be applied as needed to extend or retract the inner link 500 relative to the outer link 300 to move each set of collet finger protrusions 430 into operable engagement with a selected set of annular grooves 510 on the inner link 500 to increase or decrease the overall length of the adjustable bail extension 100 as needed.

Then the locking sleeve 440 is rotated clockwise until the locking sleeve pin hole 441 is axially aligned with the locking pin slot 303 on the outer link 300, thereby restoring the adjustment mechanism 400 to the locked position (as shown in fig. 3A), whereby the locking pin 460 is inserted into the locking sleeve pin hole 441 to prevent subsequent accidental over-counterclockwise rotation and the associated risk of the locking sleeve 440 moving axially out of the locked position. As previously described, alternative means for limiting excessive axial movement of the locking sleeve 440 when in the locked position may be implemented in the form of a set screw acting between the locking sleeve 440 and the outer link 300, or by threaded locking dogs mounted in the locking sleeve 440 and engageable with locking dog pockets formed in the outer link 300.

It will be readily understood by those skilled in the art that various modifications may be made to the embodiments of the disclosure, including modifications using equivalent structures or materials hereafter designed or developed, without departing from the scope of the present teachings.

It is to be expressly understood that the scope of the present disclosure is not intended to be limited to the embodiments illustrated or described, and that the substitution of modified forms of elements or features shown or described does not constitute a departure from the scope of the present disclosure without resulting in any substantial functional change.

For example, as shown, it is not necessary that the outer link 300 be located above the inner link 500 (although this arrangement may be most convenient in many applications). In alternate embodiments, the outer link 300 may be positioned below the inner link 500, with the elevator adapter 600 at the lower end of the outer link 300 and the link adapter 200 at the upper end of the inner link 500, and all such alternate embodiments are intended to be encompassed by the present disclosure.

In this patent document, any form of the term "comprising" is to be understood as non-limitingly including any elements or features that follow the term, but not excluding elements or features that are not explicitly mentioned. The use of the indefinite article "a" or "an" to reference an element or feature does not exclude the possibility that more than one of the element or feature is present, unless the context clearly dictates otherwise.

As used herein, the terms "connect," "engage," "couple," "attach," or any other term describing an interaction between elements is not meant to limit such interaction to direct interaction between such elements, but may also include indirect interaction between such elements, such as through an auxiliary or intervening structure.

Relational and conformational terms such as, but not limited to, "axial," "cylindrical," "circular," "non-circular," and "axially symmetric" are not intended to denote or require absolute mathematical or geometric precision. Accordingly, such terms are to be understood as merely indicating or requiring substantial precision (e.g., "substantially coaxial" or "substantially cylindrical") unless the context clearly dictates otherwise.

Unless otherwise expressly stated, any reference to a "substantially cylindrical" element is intended to mean that the element appears substantially cylindrical in cross-section, although the cross-sectional configuration of the element may vary along its length.

The terms "exemplary" and "typically" as used in this document should be understood and interpreted to represent a common usage or convention, and should not be understood or interpreted as implying substantial or no change in order.

Claims

1. A variable length structural element comprising:

(a) an elongate tubular outer member having a first end and a second end, the first end of the outer member being open to the bore of the outer member;

(b) an elongated inner member having a first end and a second end, the first end of the inner member being coaxially disposed within the bore of the outer member; and

(c) an adjustment mechanism coupled to the outer member and including an inner member locking device, wherein the adjustment mechanism is operable between:

a locking position in which the inner member locking means engages the inner member at a selected locking position on the inner member to prevent relative axial movement of the inner and outer members to enable axial loads to be transferred between the inner and outer members; and

an unlocked position in which the inner member locking means does not prevent relative axial movement of the inner and outer members.

2. A variable length structural element according to claim 1, wherein the inner member locking means comprises:

(a) a collet assembly having a collet bore and including a collet base ring coaxially coupled with the first end of the outer member so as to be axially movable therewith, wherein:

the collet base ring with a plurality of collet arms extending axially away from the first end of the outer member;

each collet arm carries collet fingers configured to engage with a locking groove formed on the outer surface of the inner member; and is

The inner member passes coaxially through the collet bore; and

(b) a cylindrical locking sleeve having a locking sleeve bore between an open first end and an open second end of the locking sleeve, wherein:

the locking sleeve coaxially surrounds the collet assembly, a portion of the locking sleeve proximate the second end coaxially overlaps the first end of the outer member, and the first end of the locking sleeve extends beyond the first end of the outer member;

the locking sleeve is coupled to the outer member by a locking sleeve coupling device, allowing axial movement of the locking sleeve relative to the outer member within a defined range, thereby enabling operation of the adjustment mechanism between the locked and unlocked positions; and is

The profile of the region of the locking sleeve bore near the first end of the locking sleeve is such that it engages with the radially outer surface of the complementary profile on the collet fingers when the adjustment mechanism is in the locked position.

3. The variable length structural element of claim 2, wherein the collet bore is cylindrical, and wherein the locking groove is an annular groove formed on the cylindrical outer surface of the inner member.

4. A variable length structural element according to claim 2, wherein the outer surface of the inner member is non-circular in the region of the inner member with the locking groove.

5. A variable length structural element according to any one of claims 2 to 4, wherein the locking sleeve coupling means comprises a threaded connection comprising:

(a) an internal thread formed in a region of the locking sleeve bore proximate the second end of the locking sleeve; and

(b) an external thread is formed on the outer member in a region proximate the first end of the outer member.

6. A variable length structural element according to any one of claims 2 to 5, further comprising axial restraint means for restraining axial movement of the locking sleeve relative to the outer member when the adjustment mechanism is in the locked position.

7. A variable length structural element according to claim 6, wherein the axial restraint means comprises:

(a) a locking pin groove formed on an outer surface of the outer member; and

(b) a transverse locking pin hole formed in the locking sleeve and arranged and configured to receive the locking pin to engage the locking pin with the locking pin slot on the outer member to limit axial movement of the locking sleeve relative to the outer member.

8. A variable length structural element according to any one of claims 2 to 7, wherein the cartridge clip arm is resiliently biased in a radial direction relative to a locked or unlocked position.

9. A variable length structural element according to claim 8, wherein the radial direction is a radially outward direction relative to the locking position.

10. A variable length structural element according to any one of claims 1 to 9, wherein the outer member is non-circular in cross-section.

11. A variable length structural element according to claim 5, wherein the outer member is non-circular in cross-section but has an axisymmetric outer surface in the region of the externally threaded portion.

12. A variable length structural element according to any one of claims 1 to 11, wherein the inner member is a solid rod.

13. A variable length structural element according to claim 12, wherein the solid bars are round bars.

14. A variable length structural element according to any one of claims 1 to 13, wherein the inner member is a tubular member.

15. A variable length structural element according to claim 14, wherein the tubular member is a round tube.

16. An adjustable bail extension comprising a variable length structural member as claimed in any one of claims 1 to 15.

17. The adjustable bail extension of claim 16, wherein the second end of the outer member carries a link adapter for connection to a lower end of a pipe elevator link suspended from a top drive on the drilling rig, and the second end of the inner member carries an elevator adapter for connection to a link mounting ear on the pipe elevator.